Selective laser melting, due to the high energy density input and the small interaction time (106 K/s), can result in an ultrafine microstructure and excellent mechanical properties. However, due to ...the nonuniform nature of the temperature distribution and the transition from liquid to solid, high residual stresses exist. High residual stresses in the parts can increase the risk of material distortion and cause many problems, such as dimensional inaccuracy or cracks. This work systematically investigated the influence of annealing on the microstructure and mechanical properties of SLM-processed AlSi7Mg alloy parts. The residual stresses relaxed significantly after annealing. The Vickers hardness and the tensile stress greatly reduced, while the elongation increased. The fracture mode of the as-fabricated sample was ductile and brittle mixed fracture, whereas the fracture morphology of the annealed sample presented many more dimples, and the elongation also increased, which indicated the ductile mode.
The spatial–temporal characteristics of changes in lengths and onsets of the four seasons in China during 1961–2020 are investigated using daily temperature observations from weather stations. The ...relationship between changes in season lengths and climate change is also explored based on annual temperature variation, the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO). The results show that lengths of spring and autumn are shorter in the plateau region but longer in the southwest compared with other regions. In the past 60 years, the onset was generally advanced for spring and summer, whereas it was delayed for autumn and winter. Lengths of summer (winter) showed an overall increase (decrease) as 10.78 days (11.74 days) from the 1960s to the 2010s, which is positively (negatively) correlated with the temperature variation. Comparatively, changes in lengths of spring and autumn are much smaller and weakly correlated with the temperature variation. However, lengths of spring and autumn significantly increased in the plateau region and parts of the southwest and decreased in the south, which is positively and negatively correlated with the temperature trend, respectively. Changes in season lengths in China are also related to the AMO and modulated by the PDO phases. At the ~55‐year scale, summer lengths and winter lengths are simultaneously affected by the AMO and the PDO. The impact of the AMO on changes in lengths of spring and autumn is mainly due to its effect on the nonlinear trend associated with long‐term climate change.
Lengths of spring and autumn are shorter in the plateau region but longer in the southwest compared with other regions in China. Lengths of spring and autumn increased in the plateau region and parts of the southwest and decreased in the south. Changes in season lengths in China are correlated with the AMO and modulated by the PDO phases.
In order to enhance the strength and wear characteristics of stainless steel, Fe-based amorphous alloy with ultra-high strength was introduced to reinforce stainless steel through selective laser ...melting. The intrigued finding was that the amorphous alloy strengthened stainless steel exhibited an increased tensile strength from 819 MPa to 1090 MPa, a lower coefficient of friction (from 0.62 to 0.49) and a higher corrosion resistance. The enhancements of properties are contributed to the oxygen purification of Y element and solid solution of Co and Mo elements, as well as the grain refinement strengthen with the introduction of the amorphous alloy.
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Carbon nanotubes/AlSi10Mg composites has drawn lots of attention in structural engineering and functional device applications due to its extraordinary high elastic modulus and mechanical strength as ...well as excellent electrical and thermal conductivities. In this study, the CNTs/AlSi10Mg composites was firstly prepared and then processed by selective laser melting. The powder preparation, SLM process, and microstructure evolution, properties were clarified. The results showed that CNTs were decomposed due to the direct interaction with the laser beam. The SLMed composites displayed a similar microstructure to that of SLMed AlSi10Mg. The common brittleness phase Al4C3 didn't form, and the carbon dispersion strengthening was observed. The electrical resistivity of the composites was reduced significantly and the hardness was improved.
•Carbon nanotubes/AlSi10Mg powder were prepared by slurry ball milling process.•Carbon nanotubes/AlSi10Mg composites were firstly prepared by SLM.•The electrical resistivity of the composites was significantly reduced and hardness was improved.
AISI 420 martensitic stainless steel with excellent corrosion resistance is an ideal choice for plastic injection molds. However, injection molds are easy to fail in high–intensity and high-pressure ...environments. Therefore, it's necessary to improve their hardness and tensile strength to prolong the service life of injection molds. In this work, Selective laser melting (SLM), an additive manufacturing technology was utilized to process 5 wt% TiC/AISI 420 composites. The influence of volumetric energy density (η) on relative density, constitutional phases, microstructure and mechanical properties were investigated. The results indicated that insufficient energy input could cause defects such as pores and crack in the parts, while a part with near-full density could be fabricated if the applied η was properly settled. The ring-like structure that was comprised of thin “metal-ceramic” interface along the grain boundary was distributed more uniform with the increase of applied η. The SLM-processed sample showed a best mechanical properties at highly applied η (320 W, 850 mm/s, η = 85.6 J/mm3). It had an elevated micro-hardness (592.2 ± 53.6 Hv), an enhanced tensile strength (1452.5 MPa) and an improved elongation (8.65%), which was higher than that of the cast AISI 420 stainless steel. The research would provide theoretical support for the application of SLM-processed AISI420 stainless steel composites.
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•SLM was utilized to fabricate TiC/AISI420 composites with various volumetric energy densities.•The ring-like TiC reinforcement were distributed more uniform as the volumetric energy density increased.•A novel microstructure that obtained from samples contributed to the grains refining and grain boundaries strengthening.•The SLM-processed TiC/AISI420 composites showed superior mechanical properties.
The lack of observational data in Taklamakan Desert makes it very difficult to study its unique boundary layer structure. As a common means of supplementing observational data, the mesoscale boundary ...layer parameterization scheme in the numerical model method is difficult to capture small-scale turbulent processes, which may lead to large deviations in simulation. In order to obtain more accurate simulation data of desert atmospheric boundary layer, nested LES into WRF (WRF-LES) was configured to simulate the seasonal variations in Taklamakan Desert. By comparing LES with the conventional boundary layer parameterization scheme, the error characteristics between the two schemes are analyzed. The results show that LES exhibits superior performance in solving key atmospheric features such as small-scale processes and low-level jet streams. The simulation results in winter and summer have great uncertainty due to the boundary condition errors, respectively. LES also shows the maximum and minimum optimization degree in summer and winter, respectively, while the simulation results in spring and autumn are relatively stable. In the analysis of turbulence parameters, there are clear seasonal differences in turbulence characteristics, and the intensity of turbulence in summer is significantly higher than that in other seasons. When turbulent activity is strong, the difference in potential temperature and horizontal wind speed simulated between the two schemes is closely related to intense turbulent kinetic energy in LES. More accurate turbulence reproduced in LES leads to the better potential temperature and horizontal wind speed simulations in summer. In addition, large-scale cloud systems can lead to considerable simulation bias. Neither scheme can accurately simulate the cloud emergence process, and large differences between the two schemes occur at this point.
Introduction
Cardiopulmonary bypass (CPB) –induced lung ischemia-reperfusion (I/R) injury remains a large challenge in cardiac surgery; up to date, no effective treatment has been found. Annexin A1 ...(AnxA1) has an anti-inflammatory effect, and it has been proven to have a protective effect on CPB-induced lung injury. However, the specific mechanism of AnxA1 in CPB-induced lung injury is not well studied. Therefore, we established a CPB-induced lung injury model to explore the relevant mechanism of AnxA1 and try to find an effective treatment for lung protection.
Methods
Male rats were randomized into five groups (n = 6, each): sham (S group), I/R exposure (I/R group), I/R + dimethyl sulfoxide (D group), I/R + Ac2-26 (AnxA1 peptide) (A group), and I/R + LY294002 (a PI3K specific inhibitor) (AL group). Arterial blood gas analysis and calculation of the oxygenation index, and respiratory index were performed. The morphological changes in lung tissues were observed under light and electron microscopes. TNF-α and IL-6 and total protein in lung bronchoalveolar lavage fluid were detected via enzyme-linked immunosorbent assay. The expressions of PI3K, Akt, and NF-κB (p65) as well as p-PI3K, p-Akt, p-NF-κB (p65), and AnxA1 were detected via western blotting.
Results
Compared with the I/R group, the A group showed the following: lower lung pathological damage score; decreased expression of IL-6 and total protein in the bronchoalveolar lavage fluid, and TNF-α in the lung; increased lung oxygenation index; and improved lung function. These imply the protective role of Ac2-26, and show that LY294002 inhibited the ameliorative preconditioning effect of Ac2-26.
Conclusion
This finding suggested that the AnxA1 peptide Ac2-26 decreased the inflammation reaction and CPB-induced lung injury in rats, the lung protective effects of AnxA1may be correlated with the activation of PI3K/Akt signaling pathway.
Lung cancer stands as the most prevalent form of cancer globally, posing a significant threat to human well-being. Due to the lack of effective and accurate early diagnostic methods, many patients ...are diagnosed with advanced lung cancer. Although surgical resection is still a potential means of eradicating lung cancer, patients with advanced lung cancer usually miss the best chance for surgical treatment, and even after surgical resection patients may still experience tumor recurrence. Additionally, chemotherapy, the mainstay of treatment for patients with advanced lung cancer, has the potential to be chemo-resistant, resulting in poor clinical outcomes. The emergence of liquid biopsies has garnered considerable attention owing to their noninvasive nature and the ability for continuous sampling. Technological advancements have propelled circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), extracellular vesicles (EVs), tumor metabolites, tumor-educated platelets (TEPs), and tumor-associated antigens (TAA) to the forefront as key liquid biopsy biomarkers, demonstrating intriguing and encouraging results for early diagnosis and prognostic evaluation of lung cancer. This review provides an overview of molecular biomarkers and assays utilized in liquid biopsies for lung cancer, encompassing CTCs, ctDNA, non-coding RNA (ncRNA), EVs, tumor metabolites, TAAs and TEPs. Furthermore, we expound on the practical applications of liquid biopsies, including early diagnosis, treatment response monitoring, prognostic evaluation, and recurrence monitoring in the context of lung cancer.
Highlights
The printability, microstructural characteristics, phase transformation behaviors, and mechanical properties of LPBF-fabricated NiTi alloys are reviewed.
Several common structures for ...LPBF-fabricated NiTi alloys are considered and their various fields of application are illustrated.
The technical challenges, limitations, and development tendencies of LPBF-fabricated NiTi alloys are put forward.
Abstract
NiTi alloys have drawn significant attentions in biomedical and aerospace fields due to their unique shape memory effect (SME), superelasticity (SE), damping characteristics, high corrosion resistance, and good biocompatibility. Because of the unsatisfying processabilities and manufacturing requirements of complex NiTi components, additive manufacturing technology, especially laser powder bed fusion (LPBF), is appropriate for fabricating NiTi products. This paper comprehensively summarizes recent research on the NiTi alloys fabricated by LPBF, including printability, microstructural characteristics, phase transformation behaviors, lattice structures, and applications. Process parameters and microstructural features mainly influence the printability of LPBF-processed NiTi alloys. The phase transformation behaviors between austenite and martensite phases, phase transformation temperatures, and an overview of the influencing factors are summarized in this paper. This paper provides a comprehensive review of the mechanical properties with unique strain-stress responses, which comprise tensile mechanical properties, thermomechanical properties (e.g. critical stress to induce martensitic transformation, thermo-recoverable strain, and SE strain), damping properties and hardness. Moreover, several common structures (e.g. a negative Poisson’s ratio structure and a diamond-like structure) are considered, and the corresponding studies are summarized. It illustrates the various fields of application, including biological scaffolds, shock absorbers, and driving devices. In the end, the paper concludes with the main achievements from the recent studies and puts forward the limitations and development tendencies in the future.
(1) In order to improve the interface bonding state between poly(p-phenylene benzobisoxazole) (PBO) fibers and a polyimide (PI) polymer matrix, as well as its effectiveness under elevated ...temperature, rare earth solution (RES) and coupling agent were employed toward PBO fibers as surface modifiers in this article, respectively. (2) The surface characteristics of the PBO fibers before and after modifications were characterized and analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The effects of the surface treatment of the PBO fibers on the flexural properties and friction and wear behaviors of the polyimide polymer matrix composites reinforced by PBO fibers (PBO/PI) were studied under normal and elevated temperature, and the morphologies of the bending fracture and the worn surface were observed through scanning electronic microscopy (SEM). (3) The results revealed that the RES modification was superior to the coupling agent modification regarding increasing the surface activity of the PBO fibers. (4) The PBO/PI composite treated by RES had higher flexural properties and more excellent anti-friction and wear resistance than the pretreated and coupling agent-treated composites under both normal and elevated temperatures.
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